Such a three-side stacker has become known from U.S. Pat. No. 4,470,750, the entire contents of which are hereby incorporated by reference in its entirety, for instance. For instance, it is used as a storage rack conveyor. A side push or guide frame is arranged on the front end, transversely to the longitudinal axis of the apparatus. Depending on the type, the side push frame is connected stationarily with the vehicle or guided in the height on a lifting mast or so. Finally, it is also possible to fix the side push frame on the front side of the cab of the vehicle, which is itself as a whole traversable in the height on the lifting mast. In this case, the three-side stacker represents an order picking apparatus. A side arm is horizontally traversable on the side push frame. The side arm consists of two portions, namely a first portion, which is guided on the side push frame, and a second portion, which is mounted to be rotatable around a vertical axis. On the second portion, there is either directly attached a holder for a load supporting means, a fork for instance, or an additional mast, for instance, on which the fork holder can be traversed in the height. With the aid of a drive, which is preferably a hydraulic one, the second portion and with this the load fork or the mast, respectively, can be pivoted around a vertical axis in an angle range of 0 to 180°. The pivoting drive has parallel hydraulic cylinders, which actuate a chain, which is turn wound around a sprocket. The sprocket is splinedly connected with a shaft portion, which is mounted in a rotational bearing of the side arm and is connected with a lifting scaffold. The hydraulic lines for the supply of the drives on the movable parts are integrated and guided in a suitable manner, such that they can follow the horizontal and rotational movement of the side arm or the lifting scaffold, respectively. Toothed racks, arranged parallel in a distance and running horizontally, are attached on the side push frame, with which sprockets or gearwheels on the side arm co-operate. The sprockets or gearwheels sit splinedly on a common torsion shaft, which is in turn driven by a suitable drive. With the aid of this drive, the side arm can be moved horizontally. The torsion shaft provides also stabilisation around an axis parallel to the longitudinal axis of the vehicle.
The rotational drive for the holder for a load receiving means or a mast on the side arm of the side push frame, respectively, requires a high expense for assembly and maintenance, as well as a big number of individual components. In addition, the drive needs a relatively large installation space.
The present invention is based on the objective to improve a three-side stacker of the type mentioned in the beginning, such that the drive for a lifting scaffold or a holder for a load receiving means on the side arm of the side push frame, respectively, needs a smaller number of individual components and requires less expense in the assembly.